Plug protection system and method

ABSTRACT

Disclosed herein is a downhole plug protection system. The system includes, a tubular having perforations in a perforated portion, a screen in fluidic communication with the tubular, and a ring in sealable communication with the tubular and attached to the screen the ring having an extended portion positioned radially outwardly of the perforated portion.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/052,919, filed on May 13, 2008, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

It is common to plug fluidic openings, such as, screens, perforationsand flow ports, for example, formed in tubular walls of drillstringmembers while the tool is being run downhole. Plugging of such flowports prevents borehole fluids from infiltrating the drillstring duringthe running process, thereby reducing the weight of the drillstringthrough the buoyancy forces generated by wellbore fluid upon thedrillstring. Further, lower density fluids can be contained within thestring to adjust buoyancy. These buoyancy forces can be particularlyhelpful when running a tool into a highly deviated or horizontalwellbore in reducing frictional forces between the tool and the wellboreby floating the tool into position.

However, scraping of the drillstring along at least some of the walls ofa wellbore during running is unavoidable. Such scraping abradesmaterials used to plug flow openings often weakening such plugging tothe point of failure, thereby allowing fluid to fill the drillstring,negating the buoyancy effect and benefits resulting therefrom.Consequently, systems and methods assisting the reliable running oftools would be well received in the art.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed herein is a downhole plug protection system. The systemincludes, a tubular having perforations in a perforated portion, ascreen in fluidic communication with the tubular, and a ring in sealablecommunication with the tubular and attached to the screen the ringhaving an extended portion positioned radially outwardly of theperforated portion.

Further disclosed herein is a method of protecting a plugged perforatedtubular while running downhole. The method includes, perforating aportion of a tubular, sealedly attaching a ring to a non-perforatedportion of the tubular, perimetrically surrounding a perforated portionwith a longitudinally extended portion of the ring, plugging theperforations, and running the plugged perforated tubular downhole.

Further disclosed herein is a method of making a protected and pluggedperforated tubular. The method includes, perforating a portion of atubular, sealedly attaching a ring to a non-perforated portion of thetubular, perimetrically surrounding a perforated portion with alongitudinally extended portion of the ring, and plugging theperforations.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 depicts a partial cross sectional view of a plug protectionsystem disclosed herein illustrated in a plugged condition;

FIG. 2 depicts a partial cross sectional view of the plug protectionsystem of FIG. 1 illustrated in a open and flowing condition; and

FIG. 3 depicts a magnified view of a portion of a plug protection systemdisclosed herein with an alternate embodiment of the perforated tubularas depicted in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

Referring to FIG. 1, an embodiment of a plug protection system 10disclosed herein is illustrated. The plug protection system 10 includes,a perforated tubular member 14, shown herein as a perforated base pipe,and a screen 18, sealedly attached to the perforated tubular member 14,by end rings 22 on opposing longitudinal ends of the screen 18. Theperforated tubular member 14, in this embodiment, has a wall 26 with aplurality of ports 30 extending therethrough in two perforated portions32. The ports 30 are openings through which fluid, such as wellborefluid, is flowable when the ports 30 are not plugged. The ports 30 maybe any of a variety of shapes, such as, round, oval, or rectangular (toform slots), for example. The ports 30 are sized to be fluidicallypluggable by any of a variety of downhole degradable materials 34, suchas paraffin, and/or polymers, for example, that are used for suchpurposes. The degradability of the materials 34 allows the ports 30 tobe opened sometime after being positioned at a desired location within awellbore 38. The degradable materials 34 may be degradable in responseto exposure to elevated temperatures, for example, that permit a welloperator to open the ports 30, when desired, by pumping steam (or otherheat source in the case of a heat degradable material) downhole to heatthe perforated tubular member 14 and the degradable material 34.Alternate degradable materials 34 include materials that degrade whenexposed to acid or other chemical compositions. Acid, for example, canbe pumped downhole to expose the materials 34 thereto when opening ofthe ports 30 is desirable.

Longitudinal extensions 42 of the end rings 22 extend perimetrically tosurround the perforated portions 32 of the perforated tubular member 14.As such, the longitudinal extensions 42 protect the perforated portions32 from direct contact with walls 46 of the wellbore 38. By preventingabrasion of the degradable material 34 against the walls 46, sealintegrity of the degradable material 34 in the ports 30 can bemaintained.

A length of the longitudinal extensions 42 can be designed to match alength of the perforated portions 32, so that none of the ports 30 areexposed to direct abrasive contact with the walls 46. Discontinuousnon-sealing standoffs 50 can be positioned between the longitudinalextensions 42 and the perforated tubular member 14 to provide structuralsupport and centering of the longitudinal extensions 42 relative to theperforated tubular member 14.

Additionally, an annular space 52 defined by the longitudinal extensions42 and the perforated portions 32 could also be plugged with pluggingmaterial 34 to increase pressure differentials required to extrude theplugging material 34. Having this additional volume of plugging material34 could also increase a time exposed to elevated temperatures or acidbefore the plugging material 34 sufficiently degrades to be forcedthrough the ports 30.

Referring to FIG. 2, a flow path for wellbore fluid from the wellbore 38to an inside of the perforated tubular 14 is illustrated in anon-plugged configuration of the plug protection system 10. The fluidflows through the screen 18 and then axially, along arrows 62, in anannular space 54 defined by the screen 18 and a non-perforated portion58 of the perforated tubular member 14. The fluid then flowslongitudinally from the annular space 54 to the annular space 52. Fromthe annular space 52 the fluid is able to flow radially inwardly, alongarrows 68, through the ports 30 in the perforated portions 32 to theinside of the perforated tubular member 14. Although the fluid flow pathhas been described herein as flowing from outside of the plug protectionsystem 10 to the inside of the perforated tubular member 14, it shouldbe understood that, in other applications, the fluid could flow indirections that are the reverse of those described herein.

Referring to FIG. 3, an alternate embodiment of a perforated portion 72of the perforated tubular member 14 is illustrated. The perforatedportion 72 includes ports 76 that are designed to increase a pressuredifferential sufficient to force the degradable material 34 to extrudethrough the ports 76. The ports 76 have tapered walls 80 that create alarger cross sectional area 84 at the outer surface 88 of the perforatedtubular member 14 than the smaller cross sectional area 92 at an innersurface 96 of the perforated tubular member 14. This constructioncreates a wedging action as the pressure differential compresses thedegradable material 34 as it forces it through the ports 76. Thetapering of the walls 80, in alternate embodiments, could be tapered atangles different to those disclosed herein. The walls 80 could even betapered to narrow at locations having greater radial dimensions toincrease an extrusion pressure biased in an inside to outside direction,for example.

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims. Also, in the drawings and the description, there have beendisclosed exemplary embodiments of the invention and, although specificterms may have been employed, they are unless otherwise stated used in ageneric and descriptive sense only and not for purposes of limitation,the scope of the invention therefore not being so limited. Moreover, theuse of the terms first, second, etc. do not denote any order orimportance, but rather the terms first, second, etc. are used todistinguish one element from another. Furthermore, the use of the termsa, an, etc. do not denote a limitation of quantity, but rather denotethe presence of at least one of the referenced item.

1. A downhole plug protection system, comprising: a tubular havingperforations in a perforated portion the perforations being plugged witha degradable material; a screen in fluidic communication with thetubular; a ring in sealable communication with the tubular and attachedto the screen the ring having an extended portion positioned radiallyoutwardly of the perforated portion; and a space between the perforatedportion and the extended portion being plugged with a degradablematerial.
 2. The downhole plug protection system of claim 1, wherein theperforated portion after being plugged is openable in response todegradation of the degradable material.
 3. The downhole plug protectionsystem of claim 2, wherein the degradable material is degradable atelevated temperatures.
 4. The downhole plug protection system of claim2, wherein the degradable material is degradable when exposed to acid.5. The downhole plug protection system of claim 1, wherein the screen ispositioned radially outwardly of a non-perforated portion of thetubular.
 6. The downhole plug protection system of claim 1, wherein theperforations are holes with a shape that is one of circular, oval andrectangular.
 7. The downhole plug protection system of claim 1, whereincross sectional areas of the perforations are greater at locations withgreater radial dimensions than at locations with lesser radialdimensions.
 8. The downhole plug protection system of claim 1, whereinthe space is annular.
 9. A method of protecting a plugged perforatedtubular while running downhole, comprising: perforating a portion of atubular; plugging the perforations with degradable material; sealedlyattaching a ring to a non-perforated portion of the tubular;perimetrically surrounding the perforated portion with a longitudinallyextended portion of the ring; plugging an annular space defined betweenthe longitudinally extended portion of the ring and the perforatedportion with degradable material; and running the plugged perforatedtubular downhole.
 10. The method of protecting a plugged perforatedtubular while running downhole of claim 9, further comprising attachinga screen to a longitudinal end of the ring.
 11. The method of protectinga plugged perforated tubular while running downhole of claim 10, furthercomprising perimetrically surrounding a non-perforated portion of theplugged perforated tubular with the screen.
 12. A method of making aprotected and plugged perforated tubular, comprising: perforating aportion of a tubular; plugging the perforations; sealedly attaching aring to a non-perforated portion of the tubular; perimetricallysurrounding the perforated portion with a longitudinally extendedportion of the ring; and plugging an annular space defined between theperforated portion and the longitudinally extended portion of the ring.13. The method of making a protected and plugged perforated tubular ofclaim 12, wherein the perforating the portion of the tubular includestapering walls of the perforations so that an outer radial portion ofeach perforation has a greater cross sectional area than an inner radialportion.